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  • File transfer eating alot of CPU

    - by Dan C.
    I'm trying to transfer a file over a IHttpHandler, the code is pretty simple. However when i start a single transfer it uses about 20% of the CPU. If i were to scale this to 20 simultaneous transfers the CPU is very high. Is there a better way I can be doing this to keep the CPU lower? the client code just sends over chunks of the file 64KB at a time. public void ProcessRequest(HttpContext context) { if (context.Request.Params["secretKey"] == null) { } else { accessCode = context.Request.Params["secretKey"].ToString(); } if (accessCode == "test") { string fileName = context.Request.Params["fileName"].ToString(); byte[] buffer = Convert.FromBase64String(context.Request.Form["data"]); string fileGuid = context.Request.Params["smGuid"].ToString(); string user = context.Request.Params["user"].ToString(); SaveFile(fileName, buffer, user); } } public void SaveFile(string fileName, byte[] buffer, string user) { string DirPath = @"E:\Filestorage\" + user + @"\"; if (!Directory.Exists(DirPath)) { Directory.CreateDirectory(DirPath); } string FilePath = @"E:\Filestorage\" + user + @"\" + fileName; FileStream writer = new FileStream(FilePath, File.Exists(FilePath) ? FileMode.Append : FileMode.Create, FileAccess.Write, FileShare.ReadWrite); writer.Write(buffer, 0, buffer.Length); writer.Close(); }

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  • Writing fortran robust and "modern" code

    - by Blklight
    In some scientific environments, you often cannot go without FORTRAN as most of the developers only know that idiom, and there is lot of legacy code and related experience. And frankly, there are not many other cross-platform options for high performance programming ( C++ would do the task, but the syntax, zero-starting arrays, and pointers are too much for most engineers ;-) ). I'm a C++ guy but I'm stuck with some F90 projects. So, let's assume a new project must use FORTRAN (F90), but I want to build the most modern software architecture out of it. while being compatible with most "recent" compilers (intel ifort, but also including sun/HP/IBM own compilers) So I'm thinking of imposing: global variable forbidden, no gotos, no jump labels, "implicit none", etc. "object-oriented programming" (modules with datatypes + related subroutines) modular/reusable functions, well documented, reusable libraries assertions/preconditions/invariants (implemented using preprocessor statements) unit tests for all (most) subroutines and "objects" an intense "debug mode" (#ifdef DEBUG) with more checks and all possible Intel compiler checks possible (array bounds, subroutine interfaces, etc.) uniform and enforced legible coding style, using code processing tools C stubs/wrappers for libpthread, libDL (and eventually GPU kernels, etc.) C/C++ implementation of utility functions (strings, file operations, sockets, memory alloc/dealloc reference counting for debug mode, etc.) ( This may all seem "evident" modern programming assumptions, but in a legacy fortran world, most of these are big changes in the typical programmer workflow ) The goal with all that is to have trustworthy, maintainable and modular code. Whereas, in typical fortran, modularity is often not a primary goal, and code is trustworthy only if the original developer was very clever, and the code was not changed since then ! (i'm a bit joking here, but not much) I searched around for references about object-oriented fortran, programming-by-contract (assertions/preconditions/etc.), and found only ugly and outdated documents, syntaxes and papers done by people with no large-scale project involvement, and dead projects. Any good URL, advice, reference paper/books on the subject?

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  • Simple imeplementation of admin/staff panel?

    - by Michael Mao
    Hi all: A new project requires a simple panel(page) for admin and staff members that : Preferably will not use SSL or any digital ceritification stuff, a simple login from via http will just be fine. has basic authentication which allows only admin to login as admin, and any staff member as of the group "staff". Ideally, the "credentials(username-hashedpassword pair)" will be stored in MySQL. is simple to configure if there is a package, or the strategy is simple to code. somewhere (PHP session?) somehow (include a script at the beginning of each page to check user group before doing anything?), it will detect any invalid user attempt to access protected page and redirect him/her to the login form. while still keeps high quality in security, something I worry about the most. Frankly I am having little knowledge about Internet security, and how modern CMS such as WordPress/Joomla do with their implementation in this. I only have one thing in my mind that I need to use a salt to hash the password (SHA1?) to make sure any hacker gets the username and password pair across the net cannot use that to log into the system. And that is what the client wants to make sure. But I really not sure where to start, any ideas? Thanks a lot in advance.

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  • A map and set which uses contiguous memory and has a reserve function

    - by edA-qa mort-ora-y
    I use several maps and sets. The lack of contiguous memory, and high number of (de)allocations, is a performance bottleneck. I need a mainly STL-compatbile map and set class which can use a contiguous block of memory for internal objects (or multiple blocks). It also needs to have a reserve function so that I can preallocate for expected sizes. Before I write my own I'd like to check what is available first. Is there something in Boost which does this? Does somebody know of an available implementation elsewhere? Intrusive collection types are not usable here as the same objects need to exist in several collections. As far as I know STL memory pools are per-type, not per instance. These global pools are not efficient with respect to memory locality in mutli-cpu/core processing. Object pools don't work as the types will be shared between instance but their pool should not. In many cases a hash map may be an option in some cases.

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  • Poor execution plans when using a filter and CONTAINSTABLE in a query

    - by Paul McLoughlin
    We have an interesting problem that I was hoping someone could help to shed some light on. At a high level the problem is as below: The following query executes quickly (1 second): SELECT SA.* FROM cg.SEARCHSERVER_ACTYS AS SA JOIN CONTAINSTABLE(CG.SEARCHSERVER_ACTYS, NOTE, 'reports') AS T1 ON T1.[Key]=SA.UNIQUE_ID but if we add a filter to the query, then it takes approximately 2 minutes to return: SELECT SA.* FROM cg.SEARCHSERVER_ACTYS AS SA JOIN CONTAINSTABLE(CG.SEARCHSERVER_ACTYS, NOTE, 'reports') AS T1 ON T1.[Key]=SA.UNIQUE_ID WHERE SA.CHG_DATE'19 Feb 2010' Looking at the execution plan for the two queries, I can see that in the second case there are two places where there are huge differences between the actual and estimated number of rows, these being: 1) For the FulltextMatch table valued function where the estimate is approx 22,000 rows and the actual is 29 million rows (which are then filtered down to 1670 rows before the join) and 2) For the index seek on the full text index, where the estimate is 1 row and the actual is 13,000 rows As a result of the estimates, the optimiser is choosing to use a nested loops join (since it assumes a small number of rows) hence the plan is inefficient. We can work around the problem by either (a) parameterising the query and adding an OPTION (OPTIMIZE FOR UNKNOWN) to the query or (b) by forcing a HASH JOIN to be used. In both of these cases the query returns in sub 1 second and the estimates appear reasonable. My question really is 'why are the estimates being used in the poorly performing case so wildly inaccurate and what can be done to improve them'? Statistics are up to date on the indexes on the indexed view being used here. Any help greatly appreciated.

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  • How do I process the configure file when cross-compiling with mingw?

    - by vy32
    I have a small open source program that builds with an autoconf configure script. I ran configure I tried to compile with: make CC="/opt/local/bin/i386-mingw32-g++" That didn't work because the configure script found include files that were not available to the mingw system. So then I tried: ./configure CC="/opt/local/bin/i386-mingw32-g++" But that didn't work; the configure script gives me this error: ./configure: line 5209: syntax error near unexpected token `newline' ./configure: line 5209: ` *_cv_*' Because of this code: # The following way of writing the cache mishandles newlines in values, # but we know of no workaround that is simple, portable, and efficient. # So, we kill variables containing newlines. # Ultrix sh set writes to stderr and can't be redirected directly, # and sets the high bit in the cache file unless we assign to the vars. ( for ac_var in `(set) 2>&1 | sed -n 's/^\(a-zA-Z_a-zA-Z0-9_*\)=.*/\1/p'`; do eval ac_val=\$$ac_var case $ac_val in #( *${as_nl}*) case $ac_var in #( *_cv_* fi Which is generated then the AC_OUTPUT is called. Any thoughts? Is there a correct way to do this?

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  • ANTLR Tree Grammar and StringTemplate Code Translation

    - by Behrooz Nobakht
    I am working on a code translation project with a sample ANTLR tree grammar as: start: ^(PROGRAM declaration+) -> program_decl_tmpl(); declaration: class_decl | interface_decl; class_decl: ^(CLASS ^(ID CLASS_IDENTIFIER)) -> class_decl_tmpl(cid={$CLASS_IDENTIFIER.text}); The group template file for it looks like: group My; program_decl_tmpl() ::= << *WHAT?* >> class_decl_tmpl(cid) ::= << public class <cid> {} >> Based on this, I have these questions: Everything works fine apart from that what I should express in WHAT? to say that a program is simply a list of class declarations to get the final generated output? Is this approach averagely suitable for not so a high-level language? I have also studied ANTLR Code Translation with String Templates, but it seems that this approach takes much advantage of interleaving code in tree grammar. Is it also possible to do it as much as possible just in String Templates?

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  • Using custom coordinates with QGraphicsScene

    - by Rob
    I am experimenting with a WYSIWYG editor that allows a user to draw shapes on a page and the Qt graphics scene support seems perfect for this. However, instead of working in pixels I want all my QGraphicsItem objects to work in tenths of a millimetre but I don't know how to achieve this. For example: // Create a scene that is the size if an A4 page (2100 = 21cm, 2970 = 29.7cm) QGraphicsScene* scene = new QGraphicsScene(0, 0, 2100, 2970); // Add a rectangle located 1cm across, 1cm down, 5cm wide and 2cm high QGraphicsItem* item = scene->addRect(100, 100, 500, 200); ... QGraphicsView* view = new QGraphicsView(scene); setCentralWidget(view); Now, when I display the scene above I want the shapes to appear at correct size for the screen DPI. Is this simply a case of using QGraphicsView::scale or do I have to do something more complicated? Note that if I was using a custom QWidget instead then I would use QPainter::setWindow and QPainter::setViewport to create a custom mapping mode but I can't see how to do this using the graphics scene support.

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  • c# web extracting programming, which libraries, examples samples please

    - by user287745
    I have just started programming and have made a few small applications in C and C#. My understanding is that programming for web and thing related to web is nowadays a very easy task. Please note this is for personnel learning, not for rent a coder or any money making. An application which can run on any Windows platform even Windows 98. The application should start automatically at a scheduled time and do the following. Connect to a site which displays stock prices summary (high low current open). Capture the data (excluding the other things in the site.) And save it to disk (an SQL database) Please note:- Internet connection is assumed to be there always. Do not want to know how to make database schema or database. The stock exchange has no law prohibiting the use of the data provided on its site, but I do not want to mention the name in case I am wrong, but it's for personal private use only. The data of summary of pricing is arranged in a table such that when copied pasted to MS Excel it automatically forms a table. need steps guidance please, examples, lbraries

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  • Help needed in grokking password hashes and salts

    - by javafueled
    I've read a number of SO questions on this topic, but grokking the applied practice of storing a salted hash of a password eludes me. Let's start with some ground rules: a password, "foobar12" (we are not discussing the strength of the password). a language, Java 1.6 for this discussion a database, postgreSQL, MySQL, SQL Server, Oracle Several options are available to storing the password, but I want to think about one (1): Store the password hashed with random salt in the DB, one column Found on SO and elsewhere is the automatic fail of plaintext, MD5/SHA1, and dual-columns. The latter have pros and cons MD5/SHA1 is simple. MessageDigest in Java provides MD5, SHA1 (through SHA512 in modern implementations, certainly 1.6). Additionally, most RDBMSs listed provide methods for MD5 encryption functions on inserts, updates, etc. The problems become evident once one groks "rainbow tables" and MD5 collisions (and I've grokked these concepts). Dual-column solutions rest on the idea that the salt does not need to be secret (grok it). However, a second column introduces a complexity that might not be a luxury if you have a legacy system with one (1) column for the password and the cost of updating the table and the code could be too high. But it is storing the password hashed with a random salt in single DB column that I need to understand better, with practical application. I like this solution for a couple of reasons: a salt is expected and considers legacy boundaries. Here's where I get lost: if the salt is random and hashed with the password, how can the system ever match the password? I have theory on this, and as I type I might be grokking the concept: Given a random salt of 128 bytes and a password of 8 bytes ('foobar12'), it could be programmatically possible to remove the part of the hash that was the salt, by hashing a random 128 byte salt and getting the substring of the original hash that is the hashed password. Then re hashing to match using the hash algorithm...??? So... any takers on helping. :) Am I close?

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  • Designing secure consumer blackberry application

    - by Kiran Kuppa
    I am evaluating a requirement for a consumer blackberry application that places high premium on security of user's data. Seems like it is an insurance company. Here are my ideas on how I could go about it. I am sure this would be useful for others who are looking for similar stuff Force the user to use device password. (I am guessing that this would be possible - though not checked it yet). Application can request notifications when the device is about to be locked and just after it has been unlocked. Encryption of application specific data can be managed at those times. Application data would be encrypted with user's password. User's credentials would be encrypted with device password. Remote backup of the data could be done over HTTPS (any better ideas are appreciated) Questions: What if the user forgets his device password. If the user forgets his application password, what is the best and secure way to reset the password? If the user losses the phone, remote backup must be done and the application data must be cleaned up. I have some ideas on how to achieve (3) and shall share them. There must be an off-line verification of the user's identity and the administrator must provide a channel using which the user must be able to send command to the device to perform the wiping of application data. The idea is that the user is ALWAYS in control of his data. Without the user's consent, even the admin must not be able to do activities such as cleaning up the data. In the above scheme of things, it appears as if the user's password need not be sent over the air to server. Am I correct? Thanks, --Kiran Kumar

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  • Matplotlib PDF export uses wrong font

    - by Konrad Rudolph
    I want to generate high-quality diagrams for a presentation. I’m using Python’s matplotlib to generate the graphics. Unfortunately, the PDF export seems to ignore my font settings. I tried setting the font both by passing a FontProperties object to the text drawing functions and by setting the option globally. For the record, here is a MWE to reproduce the problem: import scipy import matplotlib matplotlib.use('cairo') import matplotlib.pylab as pylab import matplotlib.font_manager as fm data = scipy.arange(5) for font in ['Helvetica', 'Gill Sans']: fig = pylab.figure() ax = fig.add_subplot(111) ax.bar(data, data) ax.set_xticks(data) ax.set_xticklabels(data, fontproperties = fm.FontProperties(family = font)) pylab.savefig('foo-%s.pdf' % font) In both cases, the produced output is identical and uses Helvetica (and yes, I do have both fonts installed). Just to be sure, the following doesn’t help either: matplotlib.rc('font', family = 'Gill Sans') Finally, if I replace the backend, instead using the native viewer: matplotlib.use('MacOSX') I do get the correct font displayed – but only in the viewer GUI. The PDF output is once again wrong. To be sure – I can set other fonts – but only other classes of font families: I can set serif fonts or fantasy or monospace. But all sans-serif fonts seem to default to Helvetica.

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  • Why does adding Crossover to my Genetic Algorithm gives me worse results?

    - by MahlerFive
    I have implemented a Genetic Algorithm to solve the Traveling Salesman Problem (TSP). When I use only mutation, I find better solutions than when I add in crossover. I know that normal crossover methods do not work for TSP, so I implemented both the Ordered Crossover and the PMX Crossover methods, and both suffer from bad results. Here are the other parameters I'm using: Mutation: Single Swap Mutation or Inverted Subsequence Mutation (as described by Tiendil here) with mutation rates tested between 1% and 25%. Selection: Roulette Wheel Selection Fitness function: 1 / distance of tour Population size: Tested 100, 200, 500, I also run the GA 5 times so that I have a variety of starting populations. Stop Condition: 2500 generations With the same dataset of 26 points, I usually get results of about 500-600 distance using purely mutation with high mutation rates. When adding crossover my results are usually in the 800 distance range. The other confusing thing is that I have also implemented a very simple Hill-Climbing algorithm to solve the problem and when I run that 1000 times (faster than running the GA 5 times) I get results around 410-450 distance, and I would expect to get better results using a GA. Any ideas as to why my GA performing worse when I add crossover? And why is it performing much worse than a simple Hill-Climb algorithm which should get stuck on local maxima as it has no way of exploring once it finds a local max?

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  • WPF abnormal CPU usage for animation

    - by 0xDEAD BEEF
    HI! I am developing WPF application and client reports extreamly high CPU usage (90%) (whereas i am unable to repeat that behavior). I have traced bootleneck down to these lines. It is simple glowing animation for small single led control (blinking led). What could be reason for this simple annimation taking up SO huge CPU resources? <Trigger Property="State"> <Trigger.Value> <local:BlinkingLedStatus>Blinking</local:BlinkingLedStatus> </Trigger.Value> <Trigger.EnterActions> <BeginStoryboard Name="beginStoryBoard"> <Storyboard> <DoubleAnimation Storyboard.TargetName="glow" Storyboard.TargetProperty="Opacity" AutoReverse="True" From="0.0" To="1.0" Duration="0:0:0.5" RepeatBehavior="Forever"/> </Storyboard> </BeginStoryboard> </Trigger.EnterActions> <Trigger.ExitActions> <StopStoryboard BeginStoryboardName="beginStoryBoard"/> </Trigger.ExitActions> </Trigger>

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  • Creating/Maintaining a large project-agnostic code library

    - by bufferz
    In order to reduce repetition and streamline testing/debugging, I'm trying to find the best way to develop a group of libraries that many projects can utilize. I'd like to keep individual executable relatively small, and have shared libraries for math, database, collections, graphics, etc. that were previously scattered among several projects and in many cases duplicated (bad!). This library is to be in an SVN repo and several programmers will be working on it. This library will be in constant development along with the executables that utilize it. For example, I want a code file in ProjectA to look something like the following: using MyCompany.Math.2D; //static 2D math methods using MyCompany.Math.3D; //static #D math methods using MyCompany.Comms.SQL; //static methods for doing simple SQLDB I/O using MyCompany.Graphics.BitmapOperations; //static methods that play with bitmaps So in my ProjectA solution file in VisualStudio, in order to develop/debug the MyCompany library I have to add several projects (Math, Comms, Graphics). Things get pretty cluttered and Solution files get out of date quickly between programmer SVN commits. I'm just looking for a high level approach to maintaining a large, shared code base in an SCN repository. I am fully willing to radically redesign my approach. I'm looking for that warm fuzzy feeling you get when you're design approach is spot on and development is fluid and natural. And ideas? Thanks!!

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  • What is the correct JNA mapping for UniChar on Mac OS X?

    - by Trejkaz
    I have a C struct like this: struct HFSUniStr255 { UInt16 length; UniChar unicode[255]; }; I have mapped this in the expected way: public class HFSUniStr255 extends Structure { public UInt16 length; // UInt16 is just an IntegerType with length 2 for convenience. public /*UniChar*/ char[] unicode = new char[255]; //public /*UniChar*/ byte[] unicode = new byte[255*2]; //public /*UniChar*/ UInt16[] unicode = new UInt16[255]; public HFSUniStr255() { } public HFSUniStr255(Pointer pointer) { super(pointer); } } If I use this version, I get every second character of the string into my char[] ("aits D" for "Macintosh HD".) I am assuming that this is something to do with being on a 64-bit platform and JNA mapping the value to a 32-bit wchar_t but then chopping off the high 16 bits on each wchar_t on copying them back. If I use the byte[] version, I get data which decodes correctly using the UTF-16LE charset. If I use the UInt16[] version, I get the right code point for each character but it is then inconvenient to convert them back into a string. Is there some way I can define my type as char[], and yet have it convert correctly?

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  • Caching page by parts; how to pass variables calculated in cached parts into never-cached parts?

    - by Kirzilla
    Hello, Let's imagine that I have a code like this... if (!$data = $cache->load("part1_cache_id")) { $item_id = $model->getItemId(); ob_start(); echo 'Here is the cached item id: '.$item_id; $data = ob_get_contents(); ob_end_clean(); $cache->save($data, "part1_cache_id"); } echo $data; echo never_cache_function($item_id); if (!$data_2 = $cache->load("part2_cache_id")) { ob_start(); echo 'Here is the another cached part of the page...'; $data_2 = ob_get_contents(); ob_end_clean(); $cache->save("part2_cache_id"); } echo $data_2; As far as you can see I need to pass $item_id variable into never_cache_function, but if fist part is cached (part1_cache_id) then I have no way to get $item_id value. I see the only solution - serialize all data from fist part (including $item_id value); then cache serialized string and unserialize it everytime when script is executed... Something like this... if (!$data = $cache->load("part1_cache_id")) { $item_id = $model->getItemId(); $data['item_id'] = $item_id; ob_start(); echo 'Here is the cached item id: '.$item_id; $data['html'] = ob_get_contents(); ob_end_clean(); $cache->save( serialize($data), "part1_cache_id" ); } $data = unserialize($data); echo $data['html'] echo never_cache_function($data['item_id']); Is there any other ways for doing such trick? I'm looking for the most high performance solution. Thank you UPDATED And another question is - how to implement such caching into controller without separating page into two templates? Is it possible? PS: Please, do not suggest Smarty, I'm really interested in implementing custom caching.

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  • Delphi dbExpress and Interbase: UTF8 migration steps and risks?

    - by mjustin
    Currently, our database uses Win1252 as the only character encoding. We will have to support Unicode in the database tables soon, which means we have to perform this migration for four databases and around 80 Delphi applications which run in-house in a 24/7 environment. Are there recommendations for database migrations to UTF-8 (or UNICODE_FSS) for Delphi applications? Some questions listed below. Many thanks in advance for your answers! are there tools which help with the migration of the existing databases (sizes between 250 MB and 2 GB, no Blob fields), by dumping the data, recreating the database with UNICODE_FSS or UTF-8, and loading the data back? are there known problems with Delphi 2009, dbExpress and Interbase 7.5 related to Unicode character sets? would you recommend to upgrade the databases to Interbase 2009 first? (This upgrade is planned but does not have a high priority) can we simply migrate the database and Delphi will handle the Unicode character sets automatically, or will we have to change all character field types in every Datamodule (dfm and source code) too? which strategy would you recommend to work on the migration in parallel with the normal development and maintenance of the existing application? The application runs in-house so development and database administration is done internally.

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  • Triangle numbers problem....show within 4 seconds

    - by Daredevil
    The sequence of triangle numbers is generated by adding the natural numbers. So the 7th triangle number would be 1 + 2 + 3 + 4 + 5 + 6 + 7 = 28. The first ten terms would be: 1, 3, 6, 10, 15, 21, 28, 36, 45, 55, ... Let us list the factors of the first seven triangle numbers: 1: 1 3: 1,3 6: 1,2,3,6 10: 1,2,5,10 15: 1,3,5,15 21: 1,3,7,21 28: 1,2,4,7,14,28 We can see that 28 is the first triangle number to have over five divisors. Given an integer n, display the first triangle number having at least n divisors. Sample Input: 5 Output 28 Input Constraints: 1<=n<=320 I was obviously able to do this question, but I used a naive algorithm: Get n. Find triangle numbers and check their number of factors using the mod operator. But the challenge was to show the output within 4 seconds of input. On high inputs like 190 and above it took almost 15-16 seconds. Then I tried to put the triangle numbers and their number of factors in a 2d array first and then get the input from the user and search the array. But somehow I couldn't do it: I got a lot of processor faults. Please try doing it with this method and paste the code. Or if there are any better ways, please tell me.

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  • Is there a library that can decompile a method into an Expression tree, with support for CLR 4.0?

    - by Daniel Earwicker
    Previous questions have asked if it is possible to turn compiled delegates into expression trees, for example: http://stackoverflow.com/questions/767733/converting-a-net-funct-to-a-net-expressionfunct The sane answers at the time were: It's possible, but very hard and there's no standard library solution. Use Reflector! But fortunately there are some greatly-insane/insanely-great people out there who like reverse engineering things, and they make difficult things easy for the rest of us. Clearly it is possible to decompile IL to C#, as Reflector does it, and so you could in principle instead target CLR 4.0 expression trees with support for all statement types. This is interesting because it wouldn't matter if the compiler's built-in special support for Expression<> lambdas is never extended to support building statement expression trees in the compiler. A library solution could fill the gap. We would then have a high-level starting point for writing aspect-like manipulations of code without having to mess with raw IL. As noted in the answers to the above linked question, there are some promising signs but I haven't succeeded in finding if there's been much progress since by searching. So has anyone finished this job, or got very far with it? Note: CLR 4.0 is now released. Time for another look-see.

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  • Using WCF to expose underlying process

    - by Steven
    I think I must be a little dull because I'm having so much difficulty with this. I use WCF for pretty much everything in-house, it's the most appropriate technology. I have a new Silverlight 3 app that is connecting to the WCF service and that's working fine. Where the problem begins is: Because of the expense in creating the objects within this service and the high correlation of individual objects being shared between clients I want to have a console application that basically gathers/calculates/caches all the data for the service 24/7 and the service basically connects to the console app (or whatever it is) and gets the pre-processed data. eg, think of it in terms of a stock reporting app (which it is). Person A has a portfolio of x, y z Person B has a portfolio of x, q, z, r The service needs to provide updated metrics on how their portfolio is performing. So instead of every 1 second processing person A, then person B, the app independently gathers the stock price and persons position information into memory and the service just queries the in memory result. Thanks for your help, I really am feeling dumb right now.

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  • Optimizing processing and management of large Java data arrays

    - by mikera
    I'm writing some pretty CPU-intensive, concurrent numerical code that will process large amounts of data stored in Java arrays (e.g. lots of double[100000]s). Some of the algorithms might run millions of times over several days so getting maximum steady-state performance is a high priority. In essence, each algorithm is a Java object that has an method API something like: public double[] runMyAlgorithm(double[] inputData); or alternatively a reference could be passed to the array to store the output data: public runMyAlgorithm(double[] inputData, double[] outputData); Given this requirement, I'm trying to determine the optimal strategy for allocating / managing array space. Frequently the algorithms will need large amounts of temporary storage space. They will also take large arrays as input and create large arrays as output. Among the options I am considering are: Always allocate new arrays as local variables whenever they are needed (e.g. new double[100000]). Probably the simplest approach, but will produce a lot of garbage. Pre-allocate temporary arrays and store them as final fields in the algorithm object - big downside would be that this would mean that only one thread could run the algorithm at any one time. Keep pre-allocated temporary arrays in ThreadLocal storage, so that a thread can use a fixed amount of temporary array space whenever it needs it. ThreadLocal would be required since multiple threads will be running the same algorithm simultaneously. Pass around lots of arrays as parameters (including the temporary arrays for the algorithm to use). Not good since it will make the algorithm API extremely ugly if the caller has to be responsible for providing temporary array space.... Allocate extremely large arrays (e.g. double[10000000]) but also provide the algorithm with offsets into the array so that different threads will use a different area of the array independently. Will obviously require some code to manage the offsets and allocation of the array ranges. Any thoughts on which approach would be best (and why)?

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  • "É" not getting converted to two bytes correctly.

    - by ChrisF
    Further to this question I've got a supplementary problem. I've found a track with an "É" in the title. My code: var playList = new StreamWriter(playlist, false, Encoding.UTF8); - private static void WriteUTF8(StreamWriter playList, string output) { byte[] byteArray = Encoding.UTF8.GetBytes(output); foreach (byte b in byteArray) { playList.Write(Convert.ToChar(b)); } } converts this to the following bytes: 195 137 which is being output as à followed by a square (which is an character that can't be printed in the current font). I've exported the same file to a playlist in Media Monkey at it writes the "É" as "É" - which I'm assuming is correct (as KennyTM pointed out). My question is, how do I get the "‰" symbol output? Do I need to select a different font and if so which one? UPDATE People seem to be missing the point. I can get the "É" written to the file using playList.WriteLine("É"); that's not the problem. The problem is that Media Monkey requires the file to be in the following format: #EXTINFUTF8:140,Yann Tiersen - Comptine D'Un Autre Été: L'Après Midi #EXTINF:140,Yann Tiersen - Comptine D'Un Autre Été: L'Après Midi #UTF8:04-Comptine D'Un Autre Été- L'Après Midi.mp3 04-Comptine D'Un Autre Été- L'Après Midi.mp3 Where all the "high-ascii" (for want of a better term) are written out as a pair of characters.

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  • Help, my CentOS servers keep going down , No route to host after a random uptime [closed]

    - by user249071
    Hello , I have a couple of Centos linux servers, that have a very simple task, they run nginx + fastcgi for php , and some NFS mounts between them, readonly They have some RPC commands to start some downloading processes with wget, nothing fancy , from a main server, but their behavior is very unstable, they simply go down, we tried to monitor ram , processor usage, even network connections, they don't load up so much, max network connections up to... 250 max, 15% processor usage and memory , well, doesn't even fill up, 2.5GB from 8GB max , I have no ideea why can a linux server go down like that, they aren't even public servers, no domain names installed no public serving, for sites. The only thing that I've discovered was that if i didn't restart the network service every couple of hours or so... the servers were becoming very slow, starting apps very slow, but not repoting a high usage of resources...Maybe Centos doesn't free the timeout connections, or something like that...It's based on Red Hat right? I'm not a linux expert , but I'm sure that there are a few guys out there that can easily have an answer to this , or even have some leads to what i can do ... I haven't installed snort, or other things to view if we have some DOS attacks, still the scheduled script that restarts the network each hour should put the system back online, and it doesn't.... Thank you in advance

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  • How to Manage CSS Explosion

    - by Jason
    I have been heavily relying on CSS for a website that I am working on (currently, everything is done as property values within each tag on the website and I'm trying to get away from that to make updates significantly easier). The problem I am running into, is I'm starting to get a bit of "CSS explosion" going on. It is becoming difficult for me to decide how to best organize and abstract data within the CSS file. For example: I am using a large number of div tags within the website (previously it was completely tables based). So I'm starting to get a lot of CSS that looks like this... div.title { background-color: Blue; color: White; text-align: center; } div.footer { /* Stuff Here */ } div.body { /* Stuff Here */ } etc. It's not too bad yet, but since I am learning here, I was wondering if recommendations could be made on how best to organize the various parts of a CSS file. What I don't want to get to is where I have a separate CSS attribute for every single thing on my website (which I have seen happen), and I always want the CSS file to be fairly intuitive. (P.S. I do realize this is a very generic, high-level question. My ultimate goal is to make it easy to use the CSS files and demonstrate their power to increase the speed of web development so other individuals that may work on this site in the future will also get into the practice of using them rather than hard-coding values everywhere.)

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